What scientist explained the theory of atomic structure by relating it to the planetary model?

how much sodium chloride must be added to 100 mL of water so that its concentration is 20 parts per million assume that the dens

OlgaM077 [116]

Answer: 2mg

Part per million is unit that equal to mg/kg of water or simply $10^{-6}$ . In this case, you asked how much NaCl needed and know the volume of water(100mL), concentration(20ppm or 20 mg/kg) and water density.
Then, the equation would be

concentration = NaCl weight/ water weight
20 x $10^{-6}$ mg= NaCl weight/ (100ml x 1g/ml)
NaCl weight= 20x $10^{-6}$ mg/kg x 100g
NaCl weight= 2000 x $10^{-6}$ g
NaCl weight= 2x $10^{-3}$ g = 2mg

6 0

3 years ago

The enthalpy of fusion of H2O (s) at its normal melting point is 6.01 kJ/mol. What is the entropy change for freezing 1 mole of

Rom4ik [11]

Answer:

22.01J/Kmol

Explanation:

The parameters given in this question are;

Enthalpy (H) = 6.01 kJ/mol.

Number of moles = 1

Entropy change (S) = ?

The formular relationship between entropy and enthalpy is given as;

ΔS=ΔH/T

Temperature for water at freezing point = 0C + 273 = 273 K (converting to Kelvin)

ΔS = 6.01/273

ΔS = 0.0220kJ/Kmol

ΔS = 0.02201 * 1000 = 22.01J/Kmol

3 0

3 years ago

if the density of copper is 8.9g/cm^3 and the Volume of the sample is 23.4 mL what would be the mass?

Black_prince [1.1K]

Answer:

The mass of copper = 208.26 grams.

Explanation:

Density = mass / volume

8.9 = mass / 23.4

mass = 8.9 * 23.4

= 208.26 grams.

8 0

3 years ago

An unknown substance has a density of 4G/CM three and a volume of 25 CM three. What is its mass in grams

Crank

Answer:

100g

Explanation:

Formula

Mass

Density Volume

Mass = Density X Volume

Mass=4g/cm^3 X 25cm^3

Mass =100grams

7 0

3 years ago

A chemist wants to extract a solute from 100 mL of water using only 300 mL of ether. The partition coefficient between ether and

devlian [24]

Answer:

a. X = 0,909

b. X = 0,965

c X = 0,997

Explanation:

The partition coefficient (k) is defined as:

k = Solute in ether / solute in water

a. $3,34 = \frac{\frac{X}{300mL} }{\frac{1-X}{100mL} }$

Where X is the fraction of solute extracted

3,34 = X / 3-3X

10,02-10,02X = X

10,02 = 11,02X

X = 0,909

b. First extraction:

$3,34 = \frac{\frac{X}{100mL} }{\frac{1-X}{100mL} }$

3,34 = X / 1-X

3,34 - 3,34X = X

3,34 = 4,34X

X = 0,770

That means solute in water will be: 1-0,770 = 0,23

Second extraction:

The second extraction will extract the same fraction of solute, as now you have 0,230 of solute in water you will extract:

0,230×0,770 = 0,177

Third extraction:

In the same way, the third extraction will extract:

(0,230-0,177)×0,770 = 0,018

Fraction in water×Fraction extracted

That means total solute extracted is:

0,770 + 0,177 + 0,018 = 0,965

c. Extracting with 50mL of ether:

First extraction

$3,34 = \frac{\frac{X}{50mL} }{\frac{1-X}{100mL} }$

3,34 = 2X / 1-X

3,34 - 3,34X = 2X

3,34 = 5,34X

X = 0,625

Second extraction:

(1-0,625)×0,625= 0,234

Third Extraction:

(1-0,625-0,234)×0,625= 0,088

Fourth extraction:

(1-0,625-0,234-0,088)×0,625= 0,033

Fifth extraction:

(1-0,625-0,234-0,088-0,033)×0,625= 0,013

Sixth extraction:

(1-0,625-0,234-0,088-0,033-0,013)×0,625= 0,004

Total extractions gives:

0,625+0,234+0,088+0,033+0,013+0,004 = 0,997

I hope it helps!

8 0

4 years ago

What scientist explained the theory of atomic structure by relating it to the planetary model?​

What scientist explained the theory of atomic structure by relating it to the planetary model?